What does click-through rate (CTR) measure in online advertising?

• A. The percentage of people who see your ad and click on it.
• B. The total number of clicks your ad receives.
• C. The average position of your ad on the search results page.
• D. The ratio of impressions to clicks.

Answer: (A)

CTR measures the percentage of impressions that result in a click on your ad. The option that describes CTR as the percentage of people who see your ad and click on it is the best because CTR is defined as clicks divided by impressions, expressed as a percentage. This distinguishes it from simply counting clicks (which is raw clicks), from ad position (where the ad appears), or from the ratio of impressions to clicks (which is the inverse of CTR). A higher CTR can indicate the ad and keywords are relevant and compelling to the audience, though it should be considered alongside conversions and value.